Tubular medical device

ABSTRACT

Apparatus for progressively dilating the lumen of a narrow natural vessel such as an iliac artery and implanting a tubular device enabling access through the dilated lumen to conduct subsequent procedures via the dilated lumen, includes an inflatable integrated balloon locatable at least partially within the tubular device, the tubular device having a length L 1  providing a self-expanding tubular body having at least a portion including stents, so that when the integrated balloon is removed the dilated lumen of the natural vessel remains dilated and supported by the tubular device.

RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 16/595,880,filed Oct. 8, 2019, which claims priority benefit from InternationalApplication No. PCT/GB2018/051285, filed on May 11, 2018, which claimspriority to Great Britain Patent Application No. 1707929.4, filed on May17, 2017, each of which is incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

This disclosure relates to medical devices, particularly grafts anddelivery systems for such grafts for use in treating defective nativeparts of the vasculature. The disclosure relates to procedures, deliverysystems and devices useful in any narrow lumen of a natural vessel butfor convenience will be described without limitation in relation to thevasculature where there is a significant and hitherto unmet need forsuch procedures and devices.

BACKGROUND OF THE INVENTION

Arteries may be subject to stenosis which is an abnormal narrowing ofthe lumen within the artery over time. Such narrowing may have adverseconsequences including blockage of the artery, restricted blood supplyto tissue and elevated blood pressure. Iliac arteries in particularpresent difficulties because they are often tortuous and of narrow lumendimension, and these arteries in elderly patients are more susceptibleto disease or stenosis due to atherosclerosis or calcification. An iliacarterial occlusion may lead to lower extremity issues such as reducedmobility, fatigue or cramp in the legs, and in neglected cases ordiabetic patients, to ulcers and tissue necrosis. Surgicalinterventions, such as revascularization or by-pass surgery may bepossible in some cases, but an endovascular procedure, being a minimallyinvasive procedure, often offers a more effective approach to treatmentwith less risk for the patient in most cases.

A typical endovascular procedure would be an endovascular aneurysmrepair (EVAR). Typically this involves inserting an endograft on adelivery system via a groin incision along a guidewire or catheterinserted into the femoral artery to ultimately access an aneurysmicsite, in one of the major vessels of the vasculature. However, such aprocedure can be inhibited or prevented if part of the vascular pathwayfor delivery is occluded, unduly tortuous, or otherwise of limitedpatency as in the case of stenosis of the iliac artery.

In an endovascular procedure, a manufactured medical device including atubular form part is inserted into a natural or native vessel formingpart of the vasculature as a graft substitute for a diseased or weakenedpart of the natural vessel, or as a prosthetic support for the diseasedor weakened part of the natural vessel.

SUMMARY OF THE INVENTION

The present disclosure relates to endovascular devices which may beuseful in treatment of patients suffering from defects and weaknesses inthe vasculature, and is particularly intended for those patientsrequiring treatment for stenosis of the natural iliac vessels includingthe common iliac, internal and external iliac arteries.

The iliac arteries are usually of small lumen diameter, therebyproviding limited intravascular access and requiring a low profiledevice to accomplish an endovascular procedure. Such a procedure oftenentails use of an introducer sheath which guides catheters, introduceror access guidewires, and delivers devices into the target site withinthe vasculature. It would be an objective of such an endovascularprocedure to insert a tubular device to provide a bypass bridging thediseased or weak part of the artery and to provide a substitute lumenbetween remaining healthy parts of the artery to allow throughflow ofblood. However, it has been observed that the iliac arteries areparticularly susceptible to damage such as a sheath-induced laceration.It is not unknown for removal of the introducer sheath tounintentionally rupture an iliac artery or expose a rupturable weaknessby avulsion. Therefore access to deliver a device to a target sitewithin the vasculature via the natural iliac vessels is challenging.

Such a tubular device is typically made from a physiologicallyacceptable woven fabric formed into a tubular sleeve. The tubular sleevewould be delivered in a collapsed or compact configuration within adelivery system, and may be expanded at the target site using anexpandable balloon device or enclosed resilient stents which can providesupport to the tubular sleeve and maintain the lumen thereof open toallow fluid flow through the tubular sleeve.

Due to the anticipated limited access to and through natural iliacvessels, a preliminary stage of assessment by imaging and preparationfor implanting a suitable graft may indicate that appropriate treatmentrequires successive dilation steps each progressively aiming to achievean enlargement of the target vessel in order to improve access throughand beyond the target vessel. Dilation is achievable by use ofinflatable balloon devices. However insertion of such balloon devicesinto vessels of the vasculature requires use of multiple introducersheaths/catheters which are also to be successively inserted andremoved, which actions can damage the walls of the penetrated vessels.Even in the case of careful dilation, the expansion achievable may beinsufficient to permit access for the intended graft and its associateddelivery system. In such cases an intentional rupture of the targetvessel by a surgical incision may still be necessary.

It would be of benefit if at least some of these difficulties could bealleviated or mitigated.

The present disclosure relates to apparatus for dilating the lumen of anatural vessel and implanting a tubular device to provide access throughthe dilated lumen of the natural vessel, thereby enabling access forsubsequent procedures via the dilated lumen with reduced risk of anadverse event due to manipulation of devices through the lumen of thenatural vessel.

The apparatus for dilating the lumen of a natural vessel may comprise adilation device comprising a removable expansion component such as aninflatable balloon, and a dilated lumen support component such as aself-expanding tubular body having at least a portion thereof that isstented, so that when the expansion component is removed the dilatedlumen of the natural vessel remains dilated due to the remaining lumensupport component.

The natural vessel may be part of the vasculature, especially a narrowor tortuous natural vessel such as an iliac artery. This disclosuretherefore also relates to an improved endovascular dilation device oftubular form, a delivery system for that endovascular dilation tubulardevice and a procedure for dealing with problems associated withtortuous and narrow lumen natural vessels of the vasculature. Theimplanted endovascular dilation device is expandable from an initiallycompact configuration within a removable sheath to provide access forsubsequent endovascular procedures such as advancement of devices,implements and materials to another treatment site beyond the implantedendovascular dilation device of tubular form.

The presently disclosed delivery system for a tubular device, forexample, an endovascular tubular device includes a delivery shaft and anintegrated balloon which is also in compact form within the tubulardevice and deliverable within the endovascular dilation device incompact form within the removable sheath. In an embodiment of a typicaluse of the system and tubular device, both the tubular device which isexpandable and the integrated balloon used to initiate dilation of thenatural vessel, would be delivered at the same time on the same deliveryshaft in compact form within a removable sheath. Since the tubulardevice includes a self-expanding tubular body having at least a portionthereof that is stented, when the removable sheath is removed, thetubular device will tend to expand immediately and will be limited onlyby the extent that the natural vessel has been dilated by inflation ofthe integrated balloon. Thus, in use, an endovascular lumen dilation ofa natural vessel is initiated by the integrated balloon, and maintainedby the tubular device when the integrated balloon is removed.

The endovascular tubular device may comprise a fabric sleeve and aplurality of ring stents attached to at least a length portion of thefabric sleeve.

Expansion of the natural vessel lumen dimension using a dilation devicemay be accomplished in successive steps; firstly by expansion of theintegrated balloon, and subsequently by removal of the integratedballoon on its delivery shaft, and insertion of at least one furtherdelivery shaft bearing a balloon that has greater expansion capability.It will be understood that in a narrow, fine and possibly tortuous lumenof a natural vessel, care has to be taken to avoid an adverse eventduring the desired widening of the lumen. A cautious approach usingmultiple balloons of increasing expansion capability in successive stepsminimises the risks associated with the intricate procedure required.

Apparatus for accomplishing this successive dilation procedure may be inthe form of a kit comprising an expandable tubular device, a deliverysystem including a delivery shaft with an integrated balloon, and aplurality of expandable balloons of increasing expandable size and whichare respectively deliverable on a delivery shaft after the integratedballoon has been used and withdrawn. In this way, the tortuous andnarrow lumen natural vessel may be dilated in successive steps until anacceptable lumen dimension suitable for through delivery of a device ona delivery system such as would be required for any endovascular (suchas EVAR, TEVAR, TAVR and modifications thereof etc.) procedure. Even ifit is necessary to crack open the tortuous and narrow lumen naturalvessel to obtain adequate access, the tubular device present throughoutthe dilation procedure serves as a substitute for the cracked part ofthe natural vessel and remains resident after the dilation procedure tobridge the cracked part of the dilated natural vessel and therebyprovide a continuous lumen through which devices may be delivered andprocedures carried out. Thus it will be understood that the presentdisclosure provides access via a natural lumen that would otherwise bedifficult to use without an open surgical intervention, and offersstrengthening or substitution for the tortuous and narrow lumen with theaim, for example, of pursuing an endovascular procedure withoutrequiring an open surgical intervention at the site of the tortuous andnarrow lumen natural vessel.

In embodiments, the tubular device used to support the dilated naturalvessel, and maintain the patency of the dilated natural vessel may be awholly endoluminal tubular body incorporating stents includingself-expanding stents, for example made from a shape memory material.

In some alternative embodiments, the tubular device used to support thedilated natural vessel, and maintain the patency of the dilated naturalvessel may be a wholly endoluminal tubular body that is expandedpassively under the control of the balloon(s) used for dilating thenatural vessel.

In embodiments the tubular device used to support the dilated naturalvessel, and maintain the patency of the dilated natural vessel may be ahybrid device where only a length portion of the tubular device is anendoluminal tubular body incorporating stents including self-expandingstents, for example made from a shape memory material.

In embodiments, an apparatus in kit form suitable for an endovascularpurpose includes an endovascular dilation device comprising incombination a tubular body that is configured for insertion into a lumenof a natural vessel of the vasculature in a compact form within aremovable sheath; and a delivery system comprising a delivery shaft andan integrated balloon that is also configured for insertion into a lumenof a natural vessel of the vasculature in a compact form within the sameremovable sheath, wherein the integrated balloon is one that isundersized in relation to the maximum potential expanded dimension ofthe tubular body; and a plurality of expandable balloons of differingexpandable size for successive use in expanding the tubular body, eachexpandable balloon being insertable in turn into the lumen in a compactform upon a delivery shaft for use in progressively dilating the lumenof the natural vessel of the vasculature. The kit may comprise amalleable delivery shaft, a flexible delivery shaft and optionally aguide wire or catheter.

Since the tubular body which expands at the same time as the integratedballoon, or any subsequent balloon, is used to dilate the lumen of thenatural vessel, it prevents the natural vessel collapsing after theremoval of the balloon(s) and maintains the patency of the dilated lumenof the natural vessel. Alternatively, it can be considered that theintegrated balloon acts through the tubular body so that the combinationserves as an endovascular dilation device in an endoluminal dilationapparatus.

In embodiments the tubular body may be entirely compacted within aremovable sheath for delivery with the integrated balloon on a deliveryshaft, and the tubular body may be configured to be entirely placed byan endovascular procedure. The tubular body may be fully stented with asufficient number of self-expanding stents located throughout its lengthso that after the endovascular placement procedure the tubular body isfully self-deployed when the delivery system and any lumen dilatingballoon is removed.

A tubular device suitable for use as an endovascular dilation device asdisclosed herein comprises a tubular body that is configured forinsertion into a lumen of a natural vessel of the vasculature in acompact form within a removable sheath, wherein the tubular body has alength L wherein at least one tubular length portion L¹ thereof isinitially sheathed and subsequently expandable within the lumen of thenatural vessel of the vasculature, and wherein at least one furthertubular length portion L² is positioned upon a resilient support so thatthe resilient support is usable to position the tubular body such thatthe tubular length L¹ of said tubular body is positionable within thelumen of the natural vessel and releasable from the removable sheath toprovide an open lumen within the lumen of the natural vessel of thevasculature.

The resilient support may comprise an elongate catheter, an elongateflexible shaft, or an elongate guide wire. A malleable material may beused for the resilient support, such as to form a metal rod, or a metalrod or coil co-extruded with a flexible polymer resin or flexiblecomposite resin coating, to form a delivery shaft which can be shaped bya user during a procedure to aid positioning or access to a portion ofthe natural vessel or tissue adjacent the natural vessel. The malleablematerial may be a metallic material for example stainless steel or ashape-memory metallic alloy.

In embodiments the tubular length portion L² has an internal valveproviding a fluid-tight seal around an elongate catheter, elongateflexible shaft or elongate guide wire forming part of or associated witha delivery system for the tubular device. The tubular length portion L²provides an access route for the delivery systems required in theendovascular steps of a surgical procedure intended for repairing adeteriorated part of a natural vessel, for example a vessel of thevasculature.

Optionally, an external tool may be used to clamp the length portion L²to provide fluid flow control, for example, as a haemostatic valve orstopper to minimise blood loss during any stage of the procedure, suchas placement, deployment or manipulation of devices in or through thetubular body in the natural vessel being treated.

The tubular length portion L² does not require provision of any internalsupports such as stents throughout its length, but may comprise acorrugated, or crimped sleeve of fluid-impermeable ornegligible-permeability fabric.

The unstented tubular length portion L² may have tabs or ribbon loopsattached to an outer surface to improve handling.

In embodiments the length portion L² may be significantly shorter thanthe tubular length L¹ which is positionable within the lumen of thenatural vessel.

When suitably compacted within a sheath in a delivery system or deliverydevice, the external width dimension to fit within a lumen of a naturalvessel may be in the range of from 3 mm to 6 mm. In embodiments, atubular device and the sheath used to maintain the tubular device in acompact form for delivery into a lumen of natural vessel may be in therange of from about 6 to 18 French.

The removable sheath may be made from a physiologically benign lowfriction or slip polymeric material such as polytetrafluoroethylene(PTFE). The removable sheath may alternatively be formed frompolyethyleneterephthalate (PET). The selected material should be onewhich is biocompatible and may be readily passed through natural vesselsor artificial lumens without sticking. The removable sheath may besurface treated, for example to impart or enhance hydrophilic propertiesby applying a hydrophilic coating.

Suitable polymeric flexible materials for the removable sheath may beselected from thermoplastic polymers, elastomers, and copolymers such asnylon, polyurethane, polyethylene (PE), polytetrafluoroethylene (PTFE),expanded polytetrafluoroethylene (ePTFE), fluorinated ethylenepropylene, polyether block amides (PEBA), polyimide, polyether etherketone, and polybutylene terephthalate.

The sheath may be removable by pulling using a handle, draw wire orstrap attached to the sheath.

The sheath may be designed to split (for example tear) in a predictableand controllable manner under application of appropriately appliedforce. Such force can be applied using a slitting tool which may beincorporated in the delivery system. By application of such force, thesheath may tear along its length and separate to release tubular body.

In embodiments the splittable sheath is retractable against a hubcomprising a splitter mechanism to facilitate removal of the retractedsheath from the stented tubular part after deployment within the naturalvessel.

In embodiments the splitter mechanism may comprise one or more passive(static) slitter elements disposed to present slitter blade edges in theproximal-distal axial direction of the tubular body whereby the sheathbecomes split by retraction against these slitter blade edges of thepassive slitter element(s).

In embodiments the splitter mechanism may comprise at least a pair ofslitter elements which may be provided upon or within the hub

The splitter mechanism may separate the splittable sheath in one or moreplaces, forming at least one longitudinal slit such that the sheath isremovable in one piece, or optionally in more than one piece, forexample split longitudinally into halves.

The slitter elements may be made of a plastics material such as apolyamide, for example a nylon.

In alternative embodiments the splittable sheath is designed to bepeeled or pulled apart by incorporating tear lines, perforations,pre-cut parts, or introducing sutures which facilitate separation in acontrolled manner.

An option for such an embodiment is to provide a fine pull strand thatis retrievable, passes within the splittable sheath and is attached atthe distal end of the splittable sheath, for example by a suture, thepull strand returning over the splittable sheath to the proximal end,and which is thin enough to split the splittable sheath as it iswithdrawn over the splittable sheath. A user pulling upon the pullstrand externally from the proximal end of the pull strand lifts thedistal end of the pull strand and causes the pull strand to beginsplitting the splittable sheath. Continued external pull upon the pullstrand by a user splits the splittable sheath from distal to proximalend. The proximal end of the splittable sheath may be attached to a pullwire or pull strap for retrieval of the split sheath.

The tubular body when released into the target natural vessel forms arestored lumen for blood flow and facilitates passage of devices throughthe natural vessel.

The length portion L¹ of the tubular body may be formed of a materialthat is expandable permanently to retain the expanded dimensions afteran expansion step.

In embodiments, the length portion L¹ of the tubular body may be formedof expanded polytetrafluoroethylene (ePTFE) or a polyester fabric.

Any physiologically inert or benign material such as a polyester may beused to form a tubular body that is substantially impermeable to fluids,including air, and bodily fluids.

Prosthetic grafts normally used for such replacement are typically madefrom polyester fabric, which may be woven or knitted, and may be sealedwith a sealant, for example gelatine or collagen.

The tubular body may be made of a fabric (usually a knitted or wovenfabric) of ePTFE, PTFE or polyester, polyethylene or polypropylene andmay optionally be coated to reduce friction; discourage clotting or todeliver a pharmaceutical agent. The fabric will generally be porous onat least one surface to enable cell ingrowth.

The length portion L¹ of the tubular body may be expanded when using aballoon device to dilate the lumen of a natural vessel. Balloon devicesare known in the art as for example mentioned in U.S. Pat. No.5,925,074A, EP0855171A2 and EP2676639A1. A balloon device representativeof suitable devices is available from Atrium International. Typically aballoon normally used for expansion of a device, such as a balloonexpandable graft to be presented upon a delivery shaft or catheter, hasa collapsible tubular shape with tapering ends. The tubular shape maythus present truncated cone-shaped tapered sections on the distal andproximal ends of a straight tubular profile section, which taperedsections may overlie or be fixed to tubular elements and usually admitthrough passage of a delivery wire, shaft or catheter within such atubular element. The straight tubular profile section may be expandedinto a hollow cylindrical shape. A balloon-expandable device such as agraft would be mounted onto the outside surface of the straight tubesection. Such a device is useful for the purpose of dilating the lumenof a constricted natural vessel in conjunction with deployment of thetubular body disclosed herein to provide a clear passage for accessbeyond the site of the constriction in the natural vessel.

The length portion L¹ of the tubular body may be designed to receive aballoon associated with a delivery system, which balloon is removablewith the latter. The balloon may be an integrated part of the deliverysystem such that, a device, for example a tubular body graft with aballoon expandable component, the delivery system for that device, andthe balloon, together as an assembly connected by a release wire, areinserted into the patient. The delivery system and balloon aresubsequently removed after delivery, deployment and release of thedevice.

The length portion L¹ of the tubular body may be supported in anexpanded profile by one or more stent elements, whereby the increasedlumen width dimension is preserved after the balloon is removed. Thelength portion L¹ may be described hereinafter as the “endo-section”, asit is a portion of the tubular body that is insertable first into thelumen of a natural vessel.

The stent elements may comprise ring stents, at least some of which maybe saddle shaped. Suitable stents are disclosed in WO2012/164292 A1.

The length portion L¹ of the tubular body may be expandable to a widthdimension that exceeds the size of the lumen of a normal natural vessel,i.e. a native vessel that is not constricted, diseased, weakened orsubject to stenosis. The length portion L¹ of the tubular body may beused to expand an iliac vessel and provide a reinforcement graft withinthe iliac vessel. Such a reinforcement graft offers protection to afragile vessel such as the iliac and provides an opportunity tosubsequently pass through items such as a delivery system, a componentsuch as a balloon to permit further expansion, or a graft.

In embodiments, the length portion L¹ of the tubular body may beexpandable to a width dimension in the range of from 6 mm to 14 mm.

In use, with respect to a user of the tubular device, the length portionL¹ of the tubular body is a distal portion.

The open lumen of the length portion L² may be of at least substantiallyequivalent size to the lumen of a normal natural vessel, i.e. a nativevessel that is not constricted, diseased, weakened or subject tostenosis, and dimensioned to admit a delivery system component orcompact device to pass through it. The open lumen of the length portionL² may have a width dimension in the range of from 6 mm to 14 mm.

In use, with respect to a user of the tubular device, the length portionL² of the tubular body is a proximal portion.

The tubular body may be of a material that is resistant to abrasion orphysical contacts arising from repeated passage of a delivery systemcomponent through the lumen of the tubular body as for example in atypical EVAR procedure. The material may be designed to withstand atleast 3, or 4, or 5, or more successive procedures to insert andwithdraw a delivery system component through the lumen of the tubularbody.

Suitable materials include expanded polytetrafluoroethylene (ePTFE) or apolyester fabric.

Any physiologically inert or benign material such as a polyester may beused.

Prosthetic grafts normally used for such replacement are typically madefrom polyester fabric, which may be woven or knitted, and may be sealedwith a sealant, for example gelatine or collagen.

The tubular body may be made of a fabric (usually a knitted or wovenfabric) of ePTFE, PTFE or polyester, polyethylene or polypropylene andmay optionally be coated to reduce friction; discourage clotting or todeliver a pharmaceutical agent. The fabric may be porous on at least onesurface to enable cell ingrowth.

In embodiments the material may be a polyester fabric, which may bewoven or knitted, and may be sealed with a sealant, for example gelatineor collagen.

At least a part of the material forming the tubular body may be crimpedor pleated. Use of a crimped fabric sleeve to form at least a portion ofthe tubular body provides for its adjustable length, enabling thetubular body to be stretched lengthwise, and when required curved in adesired direction.

The term “crimped” as used in the present disclosure relates to a fabricprofile having a circumferential corrugation or spiral profile whichwhen viewed from a side has a generally zig-zag outline or sinusoidalprofile wherein the exterior surface undulates from a maximum dimensionto a minimum dimension repeatedly over a substantial length of thecrimped portion of the tubular body. Such a crimped profile permitsadditional length for the crimped portion of the tubular body to beobtained by applying a longitudinal stretch. Alternatively a reducedlength can be obtained by applying a longitudinal compression.Additionally the crimp surface also accommodates bending of the crimpedportion to accommodate re-direction of the tubular body from a straightprofile to a curved profile which may be required for connection with anative vessel and to account for vascular variance in patients.

In embodiments, a portion of the tubular body has a length comprising aseries of sections, each section having a tab which may be gripped tofacilitate trimming of the length of that portion of the tubular body.

In embodiments each section has a holding loop instead of a tab whichimproves the ability to grasp and hold the tubular body for trimmingunder the slippery conditions of the surgical procedure due to thepresence of body fluids.

The tab or loop can be made of a biocompatible material which may thesame as of different from the material used for the tubular body.

In embodiments, the tubular body may be lined or coated internally witha low friction or slip-promoting material to facilitate passage ofdelivery system components or devices through the tubular body. A PTFEliner, coating or layer may be suitable for this purpose.

The thickness of the material forming the tubular body may be in therange of from 0.05 mm to 1.0 mm, preferably 0.7 mm±0.2 mm.

The tubular body may be at least in part supported by a resilientsupport which may be a stent or a series of stent elements. Suitablestent types may be ring stents but spiral, Z- or zig-zag, and tubularmesh types and combinations of any of these types with or without ringstents may also be suitable.

In embodiments, the tubular body has a length L wherein the at least onelength portion L² thereof is not supported by stents, and the at leastone further length portion L¹ is supported externally or internally bystents. The stents may be self-expanding stents. The stents may be madeof a shape memory material.

In embodiments, the tubular body has a length L wherein the at least onelength portion L¹ thereof is shorter than the at least one furtherlength portion L².

In embodiments, the tubular body has a length L wherein the at least onelength portion L¹ thereof is longer than the at least one further lengthportion L².

In embodiments, the tubular body has a length L wherein the at least onelength portion L¹ thereof is approximately the same length as the atleast one further length portion L².

In embodiments at least a portion of the tubular body is tapered.

In embodiments, the at least one further length portion L² is tapered tomatch the natural vessel width dimension.

In embodiments, the tubular body has a length L comprising the at leastone length portion L¹, the at least one further length portion L² and atleast one length portion L³ which is configured to introduce acurvature, for example pleated fabric material that is optionallystitched to retain the degree of curvature required. In embodiments theat least one length portion L³ is located between the at least onelength portion L¹ and the at least one length portion L². In embodimentsthe at least one length portion L³ is located between the at least onelength portion L¹ and at least one further length portion of the L¹type.

In embodiments the tubular body comprises at each end of its totallength L a length portion of the L² type and the total length L is madeup with at least one length portion L¹ therebetween; or, the tubularbody comprises at each end of its total length L a length portion of theof the L² type and the total length L is made up with at least onelength portion L¹ and at least one length portion L³ in alternatesuccession, so that the overall length L includes at least oneexpandable portion and at least one curve.

The tubular body may be provided with a perfusion branch extendinglaterally from the tubular body.

The perfusion branch may be formed of a fabric attached to the tubularbody to form overall a bifurcated “Y” configuration. The perfusionbranch may be made a material which is the same as that used to form thetubular body. The perfusion branch may be anastomosed to a naturalvessel in the performance of a surgical procedure.

In use the tubular body remains resident in the target natural vesselrequiring expansion or dilation or removal of an occlusion or lumenrestriction for access, so as to act as an enduring reinforcement to thetypically fragile natural vessel. In this way subsequent access foradditional procedures or interventions is facilitated with reduced riskof damage to the accessible target natural vessel.

A subsequent endovascular aneurysm repair (EVAR) for example to treat adiseased or malfunctioning part of the aorta may be conducted via theresident tubular body with reduced risk of damaging the natural vesselin which the resident tubular body is located.

Notably the said tubular body once deployed within the target naturalvessel can be expanded to a larger lumen dimension in successive naturalvessel dilation steps in a sequence using different balloon expansiondevices of ever greater inflation capability. In embodiments the tubularbody has self-expanding stents, and once the delivery sheath is removed,is only restrained by the confines of the natural vessel. In this way asthe balloon expansion device dilates the natural vessel the tubular bodyretains an expanded dimension due to the support from the self-expandingstents.

Thus the expansion procedure using a balloon within the expandabletubular body to enlarge the natural vessel can be repeated more thanonce to achieve a desired lumen dimension. In a first step the deliverysystem with integrated balloon is used to create an initial enlargementof the natural vessel dimension, and also position and deploy asupportive tubular body to maintain the initial enlargement of thenatural vessel. Where the initial enlargement of the natural vesseldimension is insufficient for a desired subsequent EVAR procedure, thedelivery system with integrated balloon is removed, and another balloonof greater expansion capability is introduced on a delivery system andinflated to cause a second enlargement of the natural vessel. This stepcan be repeated again to achieve a desired lumen dimension. In somecircumstances it may be desired or even necessary to crack a severelydamaged or occluded natural vessel such as the iliac, and tosufficiently enlarge a tubular body of a desired lumen dimension toadmit an EVAR delivery system. The enlarged tubular body remainsresident within the enlarged or cracked natural vessel to substitute forthe damaged part and maintain patency of the lumen.

A hand-held delivery system for the presently disclosed tubular devicemay comprise an elongate, malleable, “delivery” shaft, (or a functionalequivalent such as a catheter or wire) upon which the tubular device isborne and deliverable. The delivery shaft may be inserted in a lumen ofthe tubular device, via the unstented section (tubular length portionL²). The delivery shaft may pass through an introducer dry-seal/valve toinhibit bodily fluid leakage and air ingress.

The elongate, malleable delivery shaft may have an integrated balloonmounted thereon.

In use a tubular body to be used as an endovascular dilation device islocated over the integrated balloon upon the elongate, malleabledelivery shaft and the device and balloon are restrained in alow-profile compact deliverable form by applying a removable sheath overthe device and balloon.

The delivery system may further comprise a user manoeuvring controlhandle attached to one end of the elongate delivery shaft remote fromthe distal tip to allow a user to move, manipulate and control thepositioning of the delivery system, and the deployment of the tubulardevice to be deployed therefrom.

The handle may comprise a slotted housing configured to fit over andaround the elongate delivery shaft upon which a device may be mountedand constrained in a compact form within a removable sheath, the slottedhousing covering at least a part of the tubular device when positionedupon the delivery shaft.

The removable sheath may be split during removal to part the sheathlongitudinally, for example along a predetermined tear line, which maybe perforated, or slit or cut by contact with a slitter element orcutter blade as the removable sheath is pulled using a puller.

An embodiment of a delivery system may comprise a sheath removalmechanism which includes at least one slitter element for parting thesheath longitudinally to allow the constrained stented tubular part ofthe endo-section of the tubular device to expand into its deployedconfiguration, and a sheath removal element, such as a pull strap, cord,tape, wire or the like, connected to the sheath to allow removal of thesheath. The sheath may be slit whenever the pull strap is pulled tobring the sheath into contact with the slitter element

The slitter element may permit linear equal splitting of a sheath.

The slitter element may be fixed to or located within a hub that isremovably mounted upon an elongate malleable delivery shaft.

The hub may comprise two part-cylindrical parts adapted to fit aroundthe elongate delivery shaft (and guide wire when used) and be clipped orremovably fastened together.

In embodiments the hub may have protruding parts formed to have aslitting edge to provide a slitter element for splitting the sheathduring retraction of the sheath to allow deployment of the stentedtubular part of the endoprosthetic device.

The hub may have a pair of slits through which a pull strap connected oneither side of the tail of the sheath can be passed to a pull handle foruse by a user for removal of the sheath.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following description additional detail of embodiments will bedescribed by way of illustrative example with reference to theaccompanying drawings.

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention andtogether with the detailed description herein, serve to explain theprinciples of the invention. The drawings are only for purposes ofillustrating preferred embodiments and are not to be construed aslimiting the invention. It is emphasized that, in accordance with thestandard practice in the industry, various features are not drawn toscale. In fact, the dimensions of the various features may bearbitrarily increased or reduced for clarity of discussion. Theforegoing and other objects, features and advantages of the inventionare apparent from the following detailed description taken inconjunction with the accompanying drawings in which:

FIG. 1 shows a side view of an implantable tubular body comprising astented endo-section connected to an unstented section;

FIG. 2 shows a side view of the implantable tubular body shown in FIG. 1after the stented endo-section has been expanded using a balloondilator.

FIG. 3 is a view from above and to one side of another embodiment of animplantable tubular body;

FIG. 4 is a view from one side of the implantable tubular body of FIG. 3;

FIG. 5 is a view from above of the implantable tubular body of FIG. 3 ;

FIG. 6 is an end view of the implantable tubular body of FIG. 3 asviewed lengthwise from the left of FIG. 3 .

FIG. 7 illustrates schematically an initial step in a surgical procedureto locate a natural vessel, for example the iliac, by reference to theinguinal ligament, which runs from the anterior superior iliac spine tothe pubic tubercle;

FIG. 8 illustrates schematically a subsequent step in a surgicalprocedure where an initial surgical incision site is retracted laterallyto a surgeon to expose, tie off (by ligature) and make an incision intothe natural vessel, for example the iliac, to provide an access point;

FIG. 9 illustrates schematically, introduction of a guidewire to preparefor introduction of a delivery system;

FIG. 10 illustrates schematically the application of haemostat clamps,notably to a perfusion branch of a tubular device carried by thedelivery system, and the advancing of the delivery system into thenatural vessel via the incision access point;

FIG. 11 illustrates schematically the anastomosis of the perfusionbranch to the natural vessel;

FIG. 12 illustrates schematically, a step in the procedure whereby airis vented from the delivery system via an internal valve associated witha tubular part of the tubular device, and an endo-portion of the tubulardevice is deployed within the natural vessel during dilation of thelatter by means of an integrated balloon carried by the delivery systemupon which the tubular device is positioned;

FIG. 13 illustrates schematically the expansion of the deployed tubulardevice by inflation of the integrated balloon from an external fluidsupply device (syringe indicated), after which the balloon can bedeflated for removal;

FIG. 14 illustrates schematically the removal of the delivery systemwith integrated balloon through a valve located within a tubular part ofthe tubular device;

FIG. 15 illustrates schematically the inflation of a bigger ballooninserted through the valve located within the tubular device andsubsequent deflation after the tubular device has been expanded to agreater lumen dimension;

FIG. 16 illustrates schematically the removal of the deflated biggerballoon;

FIG. 17 illustrates schematically the threading of the EVAR system ontothe guidewire for subsequent introduction via the valve through thetubular device and onward through the vasculature to a site requiringdeployment of an endograft;

FIG. 18 illustrates schematically the deployed bifurcated graftintroduced by the EVAR system which system is retracted (withdrawn);

FIG. 19 illustrates schematically the removal of the guidewire,stitching closure of the part of the tubular body through which thedelivery system had gain access to the vasculature, such that the valveand excess length of the tubular device can be cut off,

FIG. 20 illustrates schematically a final tubular device placementwithin the retracted incision site;

FIG. 21 illustrates schematically the final surgical step of stitchingup the incision;

FIG. 22 illustrates handle parts of an embodiment of the deliverysystem;

FIG. 23 illustrates an embodiment of the delivery system loaded with atubular device which is in low profile compact form within a removablesheath; and

FIG. 24 illustrates a partially cutaway view of an embodiment of thedelivery system loaded with a tubular device, and integrated balloon,which are in low profile compact form within a removable sheath.

DETAILED DESCRIPTION FOR CARRYING OUT THE INVENTION

In the embodiment illustrated in FIGS. 1 and 2 , an implantable graftcomprises two tubular sections secured together for example by sutures12 to form a blood-tight seal and forming a hollow tubular body 1 havinga length dimension L comprising a tubular length portion L¹ and afurther tubular length portion L². The tubular length portion L¹ formsan endovascular section 10 and has a plurality of stents 11 which arecompressible to a compact form and expandable to support the tubularlength L¹ in an expanded (dilated) configuration. The compact form canbe held for delivery by use of a removable sheath.

The implantable graft is made of fabric in the form of a collapsiblesleeve, at least part of which 13 may be crimped or pleated. The tubularlength portion L¹ and the further tubular length portion L² respectivelymay be made of the same or different fluid-impermeable fabrics selectedfrom physiologically acceptable or benign materials such as a knitted orwoven fabric of ePTFE, PTFE or polyester, polyethylene or polypropylene.The fabric may be sealed with a sealant, for example gelatine orcollagen.

The stents 11 are separate deformable ring stents which are individuallyattached to the fabric sleeve. At least some of these stents 11,optionally all, may be made from a shape-memory metallic or plasticsmaterial so as to be self-expanding. Each of the ring stents 11 may bemade of continuous loop of resilient material such as stainless steel,or a shape memory metal alloy like nitinol (a nickel-titanium alloy) orhigh modulus polymers such as polyether ether ketone PEEK or the like,and may be attached to the endovascular section 10 by way of sutures,adhesive or heat bonding as appropriate. Each ring stent 11 may beformed from a shape memory material which may be heat set against theexternal surface of the endovascular section 10. In the depictedexample, the undulating contour of each ring stent 11 comprises acompressible memory material readily forming two peaks 20 and twovalleys 22 to form in use a ““saddle-shaped” ring stent. Use of acontinuous loop of multiple windings of nitinol wire is advantageous forthis purpose

A suitable delivery system for the implantable graft disclosed hereinincludes an integrated balloon dilator for inter alia assistingexpansion of the unsheathed endovascular section 10, and at leastinitiating dilation of the natural vessel. An example of a balloon 15,has a collapsible tubular shape with tapering ends. The tubular shapehas truncated cone-shaped tapered sections 16, 17 respectively on thedistal and proximal ends of a straight tubular profile section 18, whichtapered sections 16, 17 are fixed to a tubular element 19 to definetherebetween an expansion volume which may at its fullest extent ofexpansion exceed the initial natural volume of the corresponding lengthof the narrow lumen target natural vessel.

The narrow lumen target natural vessel may be a part of the vasculaturethat is naturally narrow and tortuous such as the iliac arteries, or anynatural vessel lumen constricted by stenosis, stricture orcalcification.

In use of this embodiment, the implantable graft overlies the integratedballoon 15 sufficiently to be expandable during inflation to providesupport to a lumen of a natural vessel dilated at least partially by theintegrated balloon, and packaged for delivery within a removable sheath,particularly such that the endovascular section 10 would be compactlysheathed for delivery into a target narrow natural vessel of thevasculature and unsheathed using a release strap or wire attached to thesheath when at least the endovascular section 10 is located in positionwithin the target natural vessel. After removal of the sheath, theballoon 15 would be inflated within the expanding or partially expandedendovascular section 10 so as to dilate the natural vessel to at least afirst extent.

Where additional dilation is required, for example to admit an EVARsystem, the delivery system and integrated balloon dilator would bewithdrawn and another balloon of greater dilation capacity would bedelivered on a suitable further delivery system, inflated to furtherdilate the natural vessel and permit additional expansion of theendovascular section 10 and then that further delivery system andballoon would be removed after deflation of the balloon. The procedurecan be repeated by substitution of further balloons until the naturalvessel is fully dilated, or event ruptured whilst the fully expandedendovascular section serves as an implantable graft lumen of a desiredlumen patency.

In an embodiment illustrated in FIGS. 3 to 6 , an implantable graft,referring first to FIG. 3 , comprises a tubular body 31 having abifurcated (Y) configuration and having a length dimension L comprisinga tubular length portion L¹ and a further tubular length portion L². Thetubular length portion L¹ forms an endovascular section 30 and has aplurality stents 41 which are compressible to a compact form andexpandable to support the tubular length L¹ in an expanded (dilated)configuration. In use, the endovascular section 30 would be sheathed fordelivery into a target natural vessel of the vasculature.

One of the bifurcated limbs serves as a perfusion branch 36 which may beanastomosed to a natural vessel 60 (FIG. 11 ) in the performance of asurgical procedure.

The other of the bifurcated limbs serves as an access branch 34 forintroduction or removal of a delivery system component, and forconducting an EVAR procedure.

At least a portion of the access branch 34 has a trimmable lengthcomprising a series of sections 37, each section having a tab or loop 38which may be gripped to facilitate trimming of the length of that branchlimb of the tubular body 31.

The implantable graft is made of fabric in the form of a collapsiblesleeve. The tubular length portion L¹ and the further tubular lengthportion L² respectively may be made of the same or differentfluid-impermeable fabrics selected from physiologically acceptable orbenign materials such as a knitted or woven fabric of ePTFE, PTFE orpolyester, polyethylene or polypropylene. The fabric may be sealed witha sealant, for example gelatine or collagen.

The endovascular section 30 includes stents 41 which are separate ringstents which are individually attached to the fabric sleeve andconfigured for final use to support a dilated fabric sleeve as “saddle”shaped stents having peak 42 and valley 43 portions.

Each of the ring stents 41 may be made of continuous loop of resilientmaterial such as stainless steel, or a shape memory metal alloy likenitinol (a nickel-titanium alloy) or high modulus polymers such aspolyether ether ketone PEEK or the like, and may be attached to thefabric sleeve by way of sutures, adhesive or heat bonding asappropriate.

Each ring stent 41 may be formed from a shape memory material which maybe heat set against the external surface of the endovascular section 30.In the depicted example (FIG. 3 ), the undulating contour of each ringstent 41 comprises a compressible memory material readily forming twopeaks 42 and two valleys 43 to form in use a ““saddle-shaped” ringstent. Use of a continuous loop of multiple windings of nitinol wire isadvantageous for this purpose.

Thus the stented endovascular section is self-expanding and can assume afully open lumen dimension after the target natural vessel is fullydilated by means of the balloon.

In use, referring to FIGS. 7 to 21 , which illustrate in “storyboard”format a surgical procedure using the embodiment of FIGS. 3 to 6 , thesurgical procedure may be conducted as follows.

After preparing the surgical field in accordance with currentrecommended medical practice, the target natural vessel, for example theiliac, is located by reference to the inguinal ligament, which runs fromthe anterior superior iliac spine to the pubic tubercle.

Then an appropriate incision is made and retracted to expose the targetiliac, which is tied off (by ligature) and an incision is made into theiliac, to provide an access point for insertion of a bifurcatedendovascular tubular device including a branch suitable for use forperfusion.

A guidewire is introduced (Seldinger wire technique) into the iliac toprepare for introduction of a delivery system with endovascular tubulardevice. An endo-section of the latter being threaded and guided into theiliac over the guidewire.

Suitable haemostat clamps are applied to the device including to aperfusion branch of a tubular device carried by the delivery system, andthe advancing of the delivery system into the iliac via the incisionaccess point is initiated sufficiently to present the perfusion branchto the iliac at a point remote from the first insertion incision point.

The perfusion branch is then anastomosed to the iliac to complete aperfusion by-pass pathway through the endovascular tubular device.

At this stage in the procedure it is possible to vent air from thedelivery system via an internal valve 62 associated with a tubular partof the tubular device, and a stented endo-portion of the tubular deviceis deployed within the natural vessel that is at least partially dilatedby means of an integrated balloon carried by the delivery system uponwhich the tubular device is positioned.

The expansion of the deployed tubular device proceeds along withinflation of the integrated balloon from an external fluid supply device(e.g. syringe indicated FIG. 13 ), after which the balloon can bedeflated for removal.

The delivery system with integrated balloon is withdrawn through a valvelocated within a tubular part of the tubular device, leaving theinflated stented endo-portion of the tubular device supporting a dilatedportion of the iliac.

Where the dilated portion of the iliac needs to be further dilated, forexample, to permit transit of an EVAR system, a larger balloon onanother delivery system can be inserted through the valve located withinthe tubular device and subsequently inflated to further expand thepreviously inflated stented endo-portion of the tubular device,whereafter the second balloon can deflated and withdrawn on its deliverysystem leaving the stented endo-portion of the tubular device in afurther expanded state to enlarge the already dilated iliac to a greaterlumen dimension. The use of further balloons of ever-increasinginflation capacity in repeated steps such as above described may beimplemented until the natural vessel is sufficiently dilated or rupturedto allow the endovascular stented tubular body portion L¹ to beadequately expanded to permit access for an EVAR system. The tubulardevice remains implanted as a resident tubular graft substituting forthe possibly ruptured iliac vessel and having sufficient lumendimensions for access to the vasculature beyond the tubular graftimplant site in the iliac.

Assuming the iliac has been sufficiently dilated by the successive useof the balloons, the resident expanded tubular device maintainssufficient patency for an EVAR system to be threaded onto the guidewire(Seldinger guidewire technique) for subsequent introduction through thetubular device and onward through the vasculature to a site requiringdeployment of an endograft.

The delivery system can be removed and the surgical procedure concludedin accordance with normal good practice.

Referring to FIG. 22 , a delivery system has an operator handle 220 formanipulation and control of the system, of which certain components areshown. The handle 220 is formed in parts and has a length designed tooverlie at least a part of a tubular device to be delivered, with alengthwise axial throughbore, and through which a wire, catheter orflexible or malleable shaft may be passed. The handle parts include, afirst handle part 221 for receiving a pull handle strap to be passedthrough to a removable sheath, a hub 222, and a slotted tapered grip223. A sheath-slitter device 224 may be incorporated within the handle,optionally upon the hub, but conveniently is presented at the front ofthe handle 220 at a distal surface of the slotted tapered grip 223.

FIG. 23 illustrates an embodiment of the delivery system loaded with atubular device 231 which is in a low profile compact form within aremovable sheath 230. A U-shaped pull handle 232 is connected by straps233 through an operator handle 220, to the removable sheath 230. In usean operator can manipulate the delivery system using the operator handle220, to advance or withdraw the delivery system with respect to aninserted guidewire (Seldinger technique) to position the tubular device231 within a natural iliac vessel. When the tubular device 231 issuitably positioned, the U-shaped pull handle 232 can be used to retractthe sheath 230 to deploy the tubular device 231 within the natural iliacvessel. After an appropriate balloon expansion step, the operator handle220 can be used to withdraw the inserted parts of the delivery system,including the deflated integrated balloon through a dry-seal/valve (FIG.14 ) integrated into an unstented limb of the tubular device.

FIG. 24 illustrates a partial cutaway view of an embodiment of theapparatus including a delivery system loaded with a tubular device 240and integrated balloon 245 which are configured in a low profile compactform within a removable sheath 241.

The tubular device 240 provides an implantable graft similar to thetubular devices 31, 231 as described above. The tubular device 240comprises two tubular sections secured together for example by sutures242 to form a blood-tight seal and forming a hollow tubular body 243having a length dimension L comprising a tubular length portion L1 and afurther tubular length portion L2. The tubular length portion L1 formsan endovascular section 250 and has a plurality of stents 244 which arecompressible to a compact form and expandable to support the tubularlength L1 in an expanded (dilated) configuration. The compact form canbe held for delivery by use of a removable sheath, as depicted. Theimplantable graft includes the integrated balloon 245 which may expandthe endovascular section 250 when the section 250 is unsheathed. Theballoon 245, has a collapsible tubular shape with tapering ends. Thetubular shape has truncated cone-shaped tapered sections 246, 247respectively on the distal and proximal ends of a straight tubularprofile section 248, which tapered sections 246, 247 are fixed to atubular element 249 to define therebetween an expansion volume which mayexceed the natural volume of the corresponding length of the targetnatural vessel. The endovascular section 250 includes the stents 244which are separate ring stents which are individually attached to thefabric sleeve and configured for final use to support a dilated fabricsleeve as “saddle” shaped stents having peak 252 and valley 253portions.

The delivery system is of the type described with reference to FIG. 23 ,having an operator handle 260 for manipulation and control of thesystem. The handle 260 is formed in parts and has a length designed tooverlie at least a part of a tubular device to be delivered, with alengthwise axial throughbore, and through which a wire, catheter orflexible or malleable shaft may be passed. The handle parts include: afirst handle part 261 for receiving a pull handle strap to be passedthrough to a removable sheath, a hub 262, and a slotted tapered grip263. A sheath-slitter device 264 may be incorporated within the handle260, optionally upon the hub, but conveniently is presented at the frontof the handle 260 at a distal surface of the slotted tapered grip 263.

The use of the embodiment of FIG. 24 is analogous to that described forthe embodiment of FIGS. 3-6 , and in a surgical procedure as describedreferring to FIGS. 7 to 21 .

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” (andany form of comprise, such as “comprises” and “comprising”), “have” (andany form of have, such as “has”, and “having”), “include” (and any formof include, such as “includes” and “including”), and “contain” (and anyform of contain, such as “contains” and “containing”) are open-endedlinking verbs. As a result, a method or device that “comprises,” “has,”“includes,” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises,” “has,” “includes,” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

The invention has been described with reference to the preferredembodiments. It will be understood that the architectural andoperational embodiments described herein are exemplary of a plurality ofpossible arrangements to provide the same general features,characteristics, and general system operation. Modifications andalterations will occur to others upon a reading and understanding of thepreceding detailed description. It is intended that the invention beconstrued as including all such modifications and alterations.

1. A delivery system, comprising: a) an operator handle (220), includinga splitter mechanism (224); b) a delivery shaft (249) extending from theoperator handle (220); c) a pull handle (232) at the operator handle(220); and d) straps (233) extending from the pull handle (232).
 2. Thedelivery system of claim 1, further including a self-expanding tubularbody (31, 243) that includes a stented tubular length portion (L¹) thatincludes self-expanding stents, and a crimped tubular length portion(L²), the crimped tubular length portion (L²) being secured to thestented tubular length portion (L¹).
 3. The delivery system of claim 2,further including a removable sheath (230, 241) radially constrictingthe stented tubular length portion (L¹) that extends through theoperator handle, wherein the delivery shaft extends to the removablesheath (230,241), whereby the removable sheath (230,241) is split bypulling on the pull handle (232).
 4. The delivery system of claim 3,further including an integrated balloon (15, 245) within theself-expanding tubular body (31, 243), whereby inflation of theintegrated balloon (15, 245) after removal of the removable sheath (230,241) enables further radial expansion of the stented tubular lengthportion (L¹) of the self-expanding tubular body (31, 243)
 5. The tubularmedical device of claim 4, wherein the integrated balloon (15, 245) isone that is undersized in relation to the maximum potential expandeddimension of the tubular body (31, 243).
 6. The tubular medical deviceof claim 2, further including an internal valve at the crimped tubularlength portion (L¹).
 7. The tubular medical device of claim 6, whereinthe valve includes an introducer seal.
 8. The tubular medical device ofclaim 2, wherein the stented tubular length portion (L¹) includessaddle-shaped ring stents (244), each of which has peak (252) and valleyportions (253).
 9. The tubular medical device of claim 2, wherein thestented tubular length portion (L¹) includes a lining of apolytetrafluoroethylene (PTFE).